The present invention relates to an image processing apparatus for a radiographic image which is photographed using radioactive rays such as X-rays or the like.
Furthermore, the present invention relates to a method determining an image area used when a radiographic image which is photographed using radioactive rays such as X-rays or the like is image-processed.
When a radiographed image is digitalized and relayed through a network, the image can be processed, transmitted, stored, and retrieved, so that a more easy medical diagnosis can be achieved. However, a radiographed image having high diagnostic capacity is required. In order to improve diagnostic appropriateness, it is necessary to conduct image-processing on the radiographed image. Among various kinds of image processing, gradation processing is achieved with only a simple apparatus and has superior effects. An example of a conventional image processing techniques of gradation processing will be described as follows.
When gradation processing is conducted on a radiographed image, a condition of the gradation processing is first determined from the statistical characteristics of data such as the maximum value, the minimum value, or a histogram of data of the entire image, and then the entire image is subjected to gradation processing.
However, the statistical characteristic of image data differs on each image data depending on factors such as a patient's FIGURE, or photographing conditions such as, for example, a radiation exposure amount, a photographing time, or a voltage on a photoelectric converter. Therefore, there arises a problem in that optimum image processing data can not be secured when image processing is conducted by determining the signal value of a predetermined portion of the image data according, for example, to the histogram.